Semiconductor memory devices such as dynamic random access memory (DRAM) devices are widely used to store data in computers and electronic products. One important criterion in a DRAM device is storage density. As semiconductor technology advances, designers strive to design new generation of DRAM device with a higher storage density.
There are many methods used in designing a DRAM device to achieve a higher density. One method is reducing the size of each of millions of cells in a DRAM device thus increasing the number of cells and consequently increasing the overall storage density of the device. Another method is stacking the cells vertically, this in effect, doubles the storage capacity. There are other methods of designing a DRAM device to achieve high storage density.
There is a need for a method to achieve even higher storage density for a DRAM device using other techniques.